require('./main.css')

const {toLowerCase,toUpperCase}=require('./b.js');

const a ='hello HELLO xx yy zz'

console.log(toLowerCase(a))
console.log(toUpperCase(a))
let oDiv=document.createElement('div');
oDiv.textContent='xxxxx'
document.body.appendChild(
    oDiv
)
module.exports=a; //commonjs 模块化方案